Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

The purpose of the study was to investigate the relationship, frequency, gender differences, situations and motivations of self-induced vomiting after drinking alcohol with disordered eating, alcohol use and psychopathology; with a nonclinical university sample of males and females in New Zealand. Participants were 102 male and 159 female university students ranging in age from 17-35 years who completed a survey designed for this study along with tests that measure eating disordered attitudes and behaviours, bulimia symptoms, depression and alcohol use. Overall, 90.04% of the sample reported that they drink alcohol and, of that subset, 57.58% of males and 42.26% of females reported having self-induced vomiting after drinking alcohol. The behaviour was related to eating pathology, depression and alcohol use with gender differences apparent. Specifically, on measures of disordered eating, females who self-induce vomiting after drinking alcohol scored higher than females who do not report the behaviour (no difference apparent for males), and overall, females scored higher than males. In terms of hazardous alcohol use, males who self-induce vomiting after drinking alcohol scored higher than males who do not with the same true for females, and overall males scored higher than females. In terms of drinking at the dependency level, individuals who reported self-induced vomiting after drinking alcohol drink at a more harmful level than those who do not (both males and females) and more males than females reported hazardous alcohol usage rates. When examining depressed symptoms, females who selfinduce vomiting after drinking alcohol reported more depressed symptoms than females who do not, with males who reported the behaviour endorsing less depressed symptoms than males who do not. Overall, females indicated more depressed symptoms than males. Persons who engaged in the behaviour were more likely to endorse it as being acceptable, with this trend being stronger for males. Females who self-induce vomiting after drinking were more likely to endorse symptoms of anorexia, bulimia and depression, whereas males who reported the behaviour were more likely to indicate harmful drinking levels, and perform the behaviour to carry on drinking. Thus, for males, self-induced vomiting after drinking alcohol was related to substance abuse whereas, for females, the behaviour may be more related to disordered eating.

The purpose of the study was to investigate the relationship, frequency, gender differences, situations and motivations of self-induced vomiting after drinking alcohol with disordered eating, alcohol use and psychopathology; with a nonclinical university sample of males and females in New Zealand. Participants were 102 male and 159 female university students ranging in age from 17-35 years who completed a survey designed for this study along with tests that measure eating disordered attitudes and behaviours, bulimia symptoms, depression and alcohol use. Overall, 90.04% of the sample reported that they drink alcohol and, of that subset, 57.58% of males and 42.26% of females reported having self-induced vomiting after drinking alcohol. The behaviour was related to eating pathology, depression and alcohol use with gender differences apparent. Specifically, on measures of disordered eating, females who self-induce vomiting after drinking alcohol scored higher than females who do not report the behaviour (no difference apparent for males), and overall, females scored higher than males. In terms of hazardous alcohol use, males who self-induce vomiting after drinking alcohol scored higher than males who do not with the same true for females, and overall males scored higher than females. In terms of drinking at the dependency level, individuals who reported self-induced vomiting after drinking alcohol drink at a more harmful level than those who do not (both males and females) and more males than females reported hazardous alcohol usage rates. When examining depressed symptoms, females who selfinduce vomiting after drinking alcohol reported more depressed symptoms than females who do not, with males who reported the behaviour endorsing less depressed symptoms than males who do not. Overall, females indicated more depressed symptoms than males. Persons who engaged in the behaviour were more likely to endorse it as being acceptable, with this trend being stronger for males. Females who self-induce vomiting after drinking were more likely to endorse symptoms of anorexia, bulimia and depression, whereas males who reported the behaviour were more likely to indicate harmful drinking levels, and perform the behaviour to carry on drinking. Thus, for males, self-induced vomiting after drinking alcohol was related to substance abuse whereas, for females, the behaviour may be more related to disordered eating.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 118-120).

Not available / text

Volatile organic compounds (VOCs) and carbon monoxide are considered the main greenhouse gas pollutants from either automotive engines or stationary sources. The increased concentration of these pollutants in air severely affects human health and causes changes in earth climate and vegetation growth rates. Ethylene is one of the VOCs closely related with photocatalytic pollution when it reacts with nitrogen oxides in the presence of sun light to form ground-level ozone. It is also responsible for quick repining of fruits and vegetables. Carbon monoxide, on the other hand, is a poisonous gas mainly released by vehicle emissions, and when inhaled in high concentrations, it causes severe health problems related to the respiratory system leading to significant rates of deaths annually in Europe and North America. Globally, The World Health Organization (WHO) estimates that seven million people die yearly due to poor air quality-related reasons which urges current and future stringent regulations to control air pollution emissions. In the past four decades, several equipment modifications and processes have been studied for reducing these emissions. Among them is the phenomenon of Electrochemical Promotion of Catalysis (EPOC) which was first reported in the early 1980s. EPOC has been successfully shown to convert automotive, indoor and industrial air pollutants such as VOCs, CO and nitrogen oxides (NOx) to harmless gases. It involves reversible changes in the catalytic properties of catalysts deposited on solid electrolytes when a small electric current or potential is applied. More recently, it was demonstrated that EPOC can be thermally induced without any electrical polarization, in analogy to the well-known phenomenon of metal-support interaction, by using noble metal nanocatalysts supported on ionically conducting materials such as yttria-stabilized zirconia (YSZ). The objective of this research is to gain deeper understanding of the factors affecting metal-support interaction between the active metal and the support to enhance their catalytic activity for environmentally-important reaction systems; specifically, ethylene and carbon monoxide oxidation as well as hydrogen fuel purification by carbon monoxide methanation. First, the activity of platinum nanoparticles deposited on carbon black, which is a conventional support used in catalysis, is studied. The effect of particle size of four Pt/C nanoparticles synthesized using a modified reduction method for ethylene (C2H4) complete catalytic oxidation is investigated. These catalysts show high activity towards C2H4 oxidation which is found to be a strongly size-dependent reaction. Full conversion of 1000 ppm C2H4 is achieved over the smallest nanoparticles (1.5 nm) at 100oC while higher temperature 170oC is required to completely oxidize ethylene over the largest nanoparticle (6.3 nm). The second stage of this research compares the catalytic activity of platinum and ruthenium nanoparticles when deposited on ionic or mixed ionic conductive vs. non ionic conductive supports for CO and VOCs oxidation. The Pt and Ru nanoparticles are deposited on yttria-stabilized zirconia (8% Y2O3-stabilised ZrO2), cerium (IV) oxide (CeO2), samarium-doped ceria (SDC), gamma-alumina (γ-Al2O3), carbon black and on novel perovskite group Sm1-xCexFeO3 (x = 0, 1, 5) resulting in ≤ 1 wt. (weight) % of Pt and Ru on each support. It is found that the nanocatalysts deposited on ionic conductive or mixed ionic conductive supports outperformed the catalysts deposited on non ionic conductors due to strong metal-support interaction that greatly affects the electronic and catalytic properties of the catalysts. The enhanced catalytic activity towards CO and C2H4 oxidation reactions is shown by earlier catalytic activity and complete conversion, lower activation energies, greater turnover frequencies and higher intrinsic rates per active surface area. To further investigate the effect of ionic conductivity of the supports and the exchange of O2- (oxygen vacancy) between the support and the catalyst surface, complete oxidation of pollutants is studied in the absence of oxygen in the gas phase. For the first time, complete oxidation of CO and C2H4 in an oxygen-free environment at low temperatures (< 250oC) is achieved, which represents the main novel finding in this research. The idea of pollutant removal in the absence of oxygen is extended to a practical reaction for fuel cells application which is hydrogen fuel purification from CO impurities at temperatures < 100oC. Moreover, the effect of particle size, pollutant concentration, operating conditions and support nature in the absence of oxygen in the gas feed is studied. It is proposed that the metal nanoparticles and the solid electrolyte form local nano-galvanic cells at the vicinity of the three-phase boundary where the anodic reaction is CO or C2H4 oxidation and the cathodic reaction is the surface partial reduction of the support. A systematic catalyst reactivation process is suggested and the catalytic activity of these nano-catalysts is studied which can be further investigated for air pollution control applications such as in vehicle catalytic converters, indoor air quality units and power plant emissions.

A self·excited system with weak nonlinearities and multifrequency parametric excitation is investigated in this study. The method of multiple scales is used to analyze the system under four different resonances relating parametric excitation frequencies with the natural frequencies. In the first case, the parametric excitation frequency is approximately equal to twice the natural frequency, λ≃2ω. In the second case, the parametric excitation frequency is approximately equal to the natural frequency, λ≃ω. The third case treats a system with two parametric excitation frequencies under the condition λ₁±λ₂≃2ω. In the last case, a two-degree-of-freedom system with natural frequencies ω, and ω, is considered and the resonance λ₁+ λ₂≃ω_r- ω_q , is analyzed. Different parameters (the 1' load amplitudes, a detuning parameter, and a system stiffness parameter) are varied in each case and the responses obtained are presented in plots. The stability of the solutions is affected by all the parameters mentioned, especially the load amplitudes and the detuning parameter. / Master of Science

Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references (p. 100-106).

The spin-glass is a peculiar magnetic phase, exhibiting non-trivial dynamics at low temperatures, characterized by an continuously evolving state without long-range order. The behavior requires some degree of disorder to occur, often in the way of impurities or random exchange energy between the spins. However, recent research have found structurally ordered systems exhibiting glassy behaviour. This project aims to further investigate these self-induced spin-glasses. The report provides a short introduction to atomistic spin-dynamics and applies the theory to study self-induced spin-glasses in hexagonal systems with the help of simulations. A variation approach was applied by running simulation using a range of spin-exchange couplings in the Heisenberg Hamiltonian. These systems were then studied by the means of their autocorrelation function and compared to known glassy systems from the Edwards-Andersson model. The resulting behaviour is presented for three different hexagonal structures and glassy behaviour is indicated in stacked hexagonal systems. It is however argued that the autocorrelation function is not sufficient to classify these systems, instead further observables are needed. Nevertheless, the method of studying self-induced spin-glasses by varying couplings in the Heisenberg Hamiltonian is promising. As even with the few spin interactions used in this report we observe the slow relaxation time associated with spin-glasses. Given some extra considerations when choosing the exchange used for the simulation, a self-induced glassy state should be able to be recreated using the method described in this report. / Spinn-glas är en speciell magnetisk fas som uppvisar icke trivial dynamik vid låga temperaturer, en kontinuerlig utveckling samt en avsaknad av ordning på stora skalor. Detta beteende kräver en viss gradav oordning för att uppstå, ofta i form av föroreningar i materialet eller slumpmässiga interaktioner mellan olika spinn. Forskning har dock visat att även strukturellt ordnade system kan uppvisa spinn-glas beteende. Därmed är målet med detta projekt att fortsätta undersöka dessa själv-inducerade spinn-glas. Rapporten ger en kort introduktion till atomistisk spinn-dynamik och applicerar denna teori för att studera själv-inducerade spin-glas i hexagonala system. I projektet simulerades system med varierande spin-interaktioner i Heisenberg Hamiltonianen. Dynamiken undersöktes med hjälp av en korrelationsfunktion som jämfördes mot kända spinn-glas från Edwards-Andersson modellen. Resultat presenteras för tre hexagonala strukturer och spinn-glas-liknande beteende observeras i de tre-dimensionella systemen. Det kan dock argumenteras att korrelationsfunktionen inte är tillräcklig för att klassificera dessa system och att mer kvantitativa mått krävs. Trots detta anses metoden, att variera spinn-interaktioner i Heisenberg Hamiltonianen, vara lovande. Detta eftersom den långa avslappningstiden associerad med spinn-glas påträffades, trots de få interaktioner som användes i denna rapport. Ett själv-inducerat spin-glass borde därmed kunna skapas med de metoder som presenteras i rapporten, givet en mer systematisk metod vid val av interaktionsparametrar för simuleringen.

Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: The Council for Scientific and Industrial Research has developed a vibration excitation system. The system is designed to excite the rotor blades of an axial compressor in the specified vibration mode and at the specified frequency. The vibration excitation system was tested on Stellenbosch University’s Rofanco compressor test bench. A two-way staggered fluid-structure interaction (FSI) model was created that was capable of simulating the vibration of the rotor blades excited by the system. The results of the FSI model were verified using available experimental data. It was concluded that the FSI model is able to recreate the vibration excited by the system to within the desired level of accuracy. In addition, the results of the FSI model showed that the vibration excitation system should be able to excite the blades in the selected vibration mode and at the selected frequency provided that the excitation frequency is close the natural frequency of the first bending mode. The results also suggested that a transient computational fluid dynamics model should be sufficient for the prediction of the aerodynamic forces acting on the rotor blades. Furthermore, a one-way staggered FSI model should be adequate for calculating the motions of the blades. / AFRIKAANSE OPSOMMING: Die Wetenskaplike en Nywerheidnavorsingsraad het ’n vibrasie-opwekkingstelsel ontwerp om die rotorlemme van ’n aksiaalvloei kompressor in die gespesifiseerde vibrasiemodus en teen die gespesifiseerde frekwensie op te wek. Die vibrasieopwekkingstelsel is met behulp van die Universiteit Stellenbosch se Rofanco kompressortoetsbank getoets. Daarna is ’n tweerigting vloeistof-struktuur-interaksie model geskep om die vibrasie van die rotorlemme, wat deur die stelsel opgewek is, te simuleer. Beskikbare eksperimentele data is gebruik om die resultate van die vloeistof-struktuur-interaksie model te bevestig. Die gevolgtrekking is gemaak dat die model wél die vibrasie van die lemme met die nodige akkuraatheid kan simuleer. Die resultate van die vloeistof-struktuur-interaksie model toon ook dat die stelsel die lemme in die gekose vibrasiemodus en teen die gekose frekwensie behoort te kan opwek, solank die opwekkingsfrekwensie na aan die natuurlike frekwensie van die eerste buigmodus is. Voorts dui die resultate daarop dat ’n berekeningsvloeimeganika model die aërodinamiese laste van die lemme sal kan voorspel. ’n Eenrigting vloeistof-struktuur-interaksie model behoort voldoende te wees om die beweging van die rotorlemme te bereken.